Various inorganic glasses have been conventionally used for optical lens applications. However, the need for a lighter and thinner lens has prompted the research and development of polymer-containing optical lenses. Polymer-containing optical components are lightweight, robust, have good formability, and can be produced on a large scale to meet increasing consumer demands.
Polymer-containing optical materials can find use as eyeglass lenses, as well as microlenses (e.g., for optical information communication), coating materials for an optical device, or core materials for an optical fiber. Manufacturing such products typically requires exposure to high temperatures; therefore a polymer having a high heat resistance is necessary in order to withstand the processing steps. For example, polymer microlenses are required to retain their shape at temperatures in excess of 240° C., since laser transmitter/transceiver modules are exposed to high temperatures during their placement on printed circuit boards by a solder re-flow process or a solder bath, especially lead-free solder processes. For this reason, only polymers with high glass transition temperatures can be used. In addition, to satisfy the requirements of various optical applications, these polymers have to be transparent with high transmission, specifically in the range of 600 nm to 1600 nanometers (nm).
Several classes of high heat polymers are known in the art. Polyetherimides are known for high heat distortion temperatures and high glass transition temperatures that make their use as coatings, molded articles, composites, and the like very attractive where high temperature resistance is desired. As such, these polymers have found wide use in shaped articles, sheet materials, and coatings for use in challenging physical environments such as aerospace applications, lighting applications, and automotive applications. Due to their high glass transition temperature and high melt viscosity, however, polyetherimides can be difficult to process into finished products.
Thermoplastic polyimides comprising sulfone linkages are also well known to withstand high temperatures while maintaining high transparency. The use of polyetherimide sulfones has been limited, however, due to poor melt processability as well as the high cost stemming from the expensive monomers required for their synthesis.
Despite the high heat polymers that are currently known, there remains a continuing need in the art for a high heat polymer composition having good thermal properties in combination with good optical properties (e.g., high heat polymer compositions that are optically transparent) to overcome the above-described technical limitations. A high heat polymer having a good balance of properties, including improved optical properties, is desirable for use in optical applications.